A gas turbine engine typically includes a fan section, a compressor section, a combustor section, and a turbine section. Air moves into the engine through the fan section. Airfoil arrays in the compressor section rotate to compress the air, which is then mixed with fuel and combusted in the combustor section. The products of combustion are expanded to rotatably drive airfoil arrays in the turbine section. Rotating the airfoil arrays in the turbine section drives rotation of the fan and compressor sections. The compressor section and turbine section each have multiple stages of blades that rotate about a central axis and multiple stages of vanes that are stationary relative to the central axis.
Gas turbine engines may have various gas-flow streams that may be kept separate from one another. The gas-flow streams may be separated by various components. The internal engine environment is exposed to temperature and pressure extremes and other harsh environmental conditions, which may affect the integrity of the components separating different gas-flow streams. Higher pressure gaspath air may tend to leak between airfoil arrays into lower pressure gaspaths. Seals may be included between the components to minimize leakage. Seal degradation may contribute to loss of performance and/or efficiency of the gas turbine engine.